1. Field of the Invention
Aspects of this invention relate generally to drive mechanisms and systems, and more particularly to multi-directional lever drive systems.
2. Description of Related Art
The following art defines the present state of this field:
U.S. Pat. No. 6,715,780 to Schaeffer is directed to a manual wheelchair system comprising of a pair of lever arms positioned on each side of the chair that actuate a propulsion system located entirely under the seat of the wheelchair. Both the push and pull stroke of the levers, unlimited by stroke angle, provide unidirectional forward propulsion to the rear wheels of the chair. This is accomplished through drive gears fitted with one-way clutches and idler gears intermeshing with them. A sprocket is attached to one drive gear, and connects to an internal shifting hub using a chain or belt. This hub could optionally be a manual or automatic unit, with the automatic shifting unit retying on sensory feedback from the rear drive wheel to determine the most efficient ratio of operation. The hub connects to the rear drive axle through another sprocket and chain combination and drives the rear wheel as the levers are manipulated. The rear axle has a disconnecting clutch so that the entire drive propulsion system can be disengaged from the chair. This allows the operator to use the wheelchair in a conventional manner (by hand directly at the wheel handrails).
U.S. Pat. Nos. 6,893,035 and 7,261,309 to Watwood are directed to a wheelchair which shifts between forward and reverse by virtue of a roller mechanism which grabs in one direction and slips in the opposite direction, thereby preventing binding. The shift mechanism is initiated by rotation of a shift paddle which is located on an extremity of a lever arm remote from the roller mechanism.
U.S. Pat. Nos. 7,963,539 and 8,540,266 to Baker are directed to a wheelchair comprising a main frame and a seat mounted on the main frame. A pair of front wheels and a pair of rear wheels are also mounted on the frame. A propulsion mechanism is provided for driving the rear wheels, the propulsion mechanism comprising an arm lever for forward and back movement and a gear train between the arm lever and the rear wheels.
U.S. Pat. No. 8,186,699 to Green is directed to a manual propulsion mechanism for wheelchairs that utilizes a lever pivotally mounted to the hub of each rear wheel such that the wheelchair user can propel the chair with push/pull movements of the levers. Forward and reverse propulsion directions are accomplished by a system of one-way reversible clutches contained in the propulsion wheel hubs which also allow the levers to be operationally disconnected such that the chair can freewheel. Operator control of direction shifting is through pivoting motions imparted to the grip handles of the propulsion levers. In a preferred embodiment, improved ergonomics thr propulsion direction changes are made possible by coordinating the direction of the shift pivot motion with the push/pull movement of the levers. This allows the operator to retain a comfortable, stable grip on the grip handle while simultaneously propelling and controlling direction of movement.
U.S. Patent Application Publication No. 20130015632 to Amos Winter is directed to a manually powered wheelchair including a first lever associated with a first rear wheel and demountably coupled to a first drivetrain, the first lever having a first brake thereon. The wheelchair also includes a second lever associated with a second rear wheel and demountably coupled to a second drivetrain, the second lever having a second brake thereon. Each drivetrain includes a chainring, a chain, and a freewheel, and each drivetrain has a fixed gear ratio. The freewheel of each drivetrain is actuated by manual pivoting of the lever associated therewith. In use, the wheelchair achieves changes in mechanical advantage when a user shifts the user's hands up and down the first and second levers.
European Patent Application Publication No. EP2586570 to Weiyi Wang is directed to a bidirectional mechanical converting unit, comprising: a main shaft, a driving mechanism, which includes a driving means and a reversing means which are coupled to each other, and a rotation means for inputting torque, a rotation axis of the rotation means being coaxial with the main shaft, the rotation means and the driving mechanism being coupled to each other, and the driving mechanism delivering the torque to output at the main shaft at a predetermined direction, no matter in which direction the rotation means rotates, wherein the predetermined direction can be switched via the reversing means.
The prior art described above teaches various wheelchairs and wheelchair drive mechanisms and a two-way mechanical converter, but does not teach a lever mechanism that drives a unidirectional output from both push and pull stroke of the lever, and enables the user to change the output drive direction from the distal end of the lever, where the input torque is applied. Aspects of the present invention fulfill these needs and provide further related advantages as described in the following summary.